**3. Indoor**

Closely related to water is another garden motif created in the Renaissance the *grotta*. 2 In built cavities, garden visitors and users were able to escape from

<sup>2</sup> The grotta (It.) is an artificial cavity or a cave that mimics natural cavities. The grotta can be artistically sophisticated (such as nymphaeum), or it may have humorous motifs, or be focused on sound effects. It was already popular in the Renaissance and even more so in the time of Mannerism. It was first mentioned by Leon Battista Alberti. With its humid and cool climate, it is a pleasant place to stay in the summer. Grottas are usually decorated with shells, snails, pebbles, and minerals (oysters, pearls, brass, tuff, colored enamel, etc.; [6, 7]).

the heat or hustle and bustle of events in the garden, to cool themselves down, marvel at the sounds of water and wind, read stories embodied in sculptural decoration, and chase the glare of water on artificial cave walls, often claded with shells. For urban horticulture, these artificial caves could be quite interesting because it is not difficult to integrate them into the built structures of cities. They could find their place in a small square, on the roofs of apartment houses, or in steep slopes of riverbeds. A grotta has its own closed water system and can even allow plants to thrive in its wet and humid environment. In addition, in Baroque gardens the grotta was often a part of an architectural structure that provided space for an artificial cave in the lower part, while in the upper part one could find a pavilion, a festive hall, or a kind of viewpoint. Here, the visitors liked to linger, enjoy the view, and listen to the sounds of water coming from the grotta. Often, the sound of the water was also used as an accompaniment to small concerts on the upper floor. Such two-story garden facilities in historic gardens were also intended for other functions (the range of garden houses and architectural scenery in gardens expanded in the late eighteenth century with the English landscape style); from banquets, events, spectacles, games, music pavilions to guest rooms in the upper floor and to retreat rooms, artisan workshops, or cold stores in the lower part. The lower part of such buildings was often dug into the slopes, thus providing a constant temperature. Already in the Baroque period (or since the time of Catherine de'Medici in the sixteenth century when ice cream was invented), the nobility liked to place cold stores in the vicinity of their mansions. Ice was brought into these cold rooms in the winter, accumulated in large quantities in the middle of a usually centrally designed room, where it was preserved and helped refrigerate food for as long as 6 months [9, 14, 15]. Would such a cold store also benefit a modern city in the time of global warming (instead of electronic devices which, when cooling, also emit large amounts of heat)?
